This chapter examined the effects of densification and randomness of infrastructure in future cellular networks by employing analytical tools from stochastic geometry. Various operational scenarios were investigated, including uplink and downlink transmissions, multi-tier networks, and variable traffic load, as well as parameters and metrics of interest such as SIR, user rate, degrees of freedom, and multiple access schemes. It was shown that randomness of AP positions introduces an unavoidable but moderate performance degradation compared to a regular placement pattern. Surprisingly enough, densification of randomly placed infrastructure does not (statistically) degrade performance in terms of SIR or user rate, even under the worst case scenario where all nodes are transmitting. Taking into account inactive transmitters (due to having no associated receivers), densification results in performance improvements. Performance gains were explicitly quantified with simple closed-form expressions in most cases.